摘要

Hive内部提供了很多函数给开发者使用，包括数学函数，类型转换函数，条件函数，字符函数，聚合函数，表生成函数等等，这些函数都统称为内置函数。

 

目录

 

 

数学函数

Return Type	Name (Signature)	Description
DOUBLE	round(DOUBLE a)	Returns the rounded BIGINT value of a. 返回对a四舍五入的BIGINT值
DOUBLE	round(DOUBLE a, INT d)	Returns a rounded to d decimal places. 返回DOUBLE型d的保留n位小数的DOUBLW型的近似值
DOUBLE	bround(DOUBLE a)	Returns the rounded BIGINT value of a using HALF_EVEN rounding mode (as of ). Also known as Gaussian rounding or bankers' rounding. Example: bround(2.5) = 2, bround(3.5) = 4. 银行家舍入法（1~4：舍，6~9：进，5->前位数是偶：舍，5->前位数是奇：进）
DOUBLE	bround(DOUBLE a, INT d)	Returns a rounded to d decimal places using HALF_EVEN rounding mode (as of ). Example: bround(8.25, 1) = 8.2, bround(8.35, 1) = 8.4. 银行家舍入法,保留d位小数
BIGINT	floor(DOUBLE a)	Returns the maximum BIGINT value that is equal to or less than a 向下取整，最数轴上最接近要求的值的左边的值  如：6.10->6   -3.4->-4
BIGINT	ceil(DOUBLE a), ceiling(DOUBLE a)	Returns the minimum BIGINT value that is equal to or greater than a. 求其不小于小给定实数的最小整数如：ceil(6) = ceil(6.1)= ceil(6.9) = 6
DOUBLE	rand(), rand(INT seed)	Returns a random number (that changes from row to row) that is distributed uniformly from 0 to 1. Specifying the seed will make sure the generated random number sequence is deterministic. 每行返回一个DOUBLE型随机数seed是随机因子
DOUBLE	exp(DOUBLE a), exp(DECIMAL a)	Returns ea where e is the base of the natural logarithm. Decimal version added in . 返回e的a幂次方， a可为小数
DOUBLE	ln(DOUBLE a), ln(DECIMAL a)	Returns the natural logarithm of the argument a. Decimal version added in . 以自然数为底d的对数，a可为小数
DOUBLE	log10(DOUBLE a), log10(DECIMAL a)	Returns the base-10 logarithm of the argument a. Decimal version added in . 以10为底d的对数，a可为小数
DOUBLE	log2(DOUBLE a), log2(DECIMAL a)	Returns the base-2 logarithm of the argument a. Decimal version added in . 以2为底数d的对数，a可为小数
DOUBLE	log(DOUBLE base, DOUBLE a) log(DECIMAL base, DECIMAL a)	Returns the base-base logarithm of the argument a. Decimal versions added in . 以base为底的对数，base 与 a都是DOUBLE类型
DOUBLE	pow(DOUBLE a, DOUBLE p), power(DOUBLE a, DOUBLE p)	Returns ap. 计算a的p次幂
DOUBLE	sqrt(DOUBLE a), sqrt(DECIMAL a)	Returns the square root of a. Decimal version added in . 计算a的平方根
STRING	bin(BIGINT a)	Returns the number in binary format (see ). 计算二进制a的STRING类型，a为BIGINT类型
STRING	hex(BIGINT a) hex(STRING a) hex(BINARY a)	If the argument is an INT or binary, hex returns the number as a STRING in hexadecimal format. Otherwise if the number is a STRING, it converts each character into its hexadecimal representation and returns the resulting STRING. (See, BINARY version as of Hive .) 计算十六进制a的STRING类型，如果a为STRING类型就转换成字符相对应的十六进制
BINARY	unhex(STRING a)	Inverse of hex. Interprets each pair of characters as a hexadecimal number and converts to the byte representation of the number. (BINARY version as of Hive , used to return a string.) hex的逆方法
STRING	conv(BIGINT num, INT from_base, INT to_base), conv(STRING num, INT from_base, INT to_base)	Converts a number from a given base to another (see ). 将GIGINT/STRING类型的num从from_base进制转换成to_base进制
DOUBLE	abs(DOUBLE a)	Returns the absolute value. 计算a的绝对值
INT or DOUBLE	pmod(INT a, INT b), pmod(DOUBLE a, DOUBLE b)	Returns the positive value of a mod b. a对b取模
DOUBLE	sin(DOUBLE a), sin(DECIMAL a)	Returns the sine of a (a is in radians). Decimal version added in . 求a的正弦值
DOUBLE	asin(DOUBLE a), asin(DECIMAL a)	Returns the arc sin of a if -1<=a<=1 or NULL otherwise. Decimal version added in . 求d的反正弦值
DOUBLE	cos(DOUBLE a), cos(DECIMAL a)	Returns the cosine of a (a is in radians). Decimal version added in . 求余弦值
DOUBLE	acos(DOUBLE a), acos(DECIMAL a)	Returns the arccosine of a if -1<=a<=1 or NULL otherwise. Decimal version added in . 求反余弦值
DOUBLE	tan(DOUBLE a), tan(DECIMAL a)	Returns the tangent of a (a is in radians). Decimal version added in . 求正切值
DOUBLE	atan(DOUBLE a), atan(DECIMAL a)	Returns the arctangent of a. Decimal version added in . 求反正切值
DOUBLE	degrees(DOUBLE a), degrees(DECIMAL a)	Converts value of a from radians to degrees. Decimal version added in . 奖弧度值转换角度值
DOUBLE	radians(DOUBLE a), radians(DOUBLE a)	Converts value of a from degrees to radians. Decimal version added in . 将角度值转换成弧度值
INT or DOUBLE	positive(INT a), positive(DOUBLE a)	Returns a. 返回a
INT or DOUBLE	negative(INT a), negative(DOUBLE a)	Returns -a. 返回a的相反数
DOUBLE or INT	sign(DOUBLE a), sign(DECIMAL a)	Returns the sign of a as '1.0' (if a is positive) or '-1.0' (if a is negative), '0.0' otherwise. The decimal version returns INT instead of DOUBLE. Decimal version added in . 如果a是正数则返回1.0，是负数则返回-1.0，否则返回0.0
DOUBLE	e()	Returns the value of e. 数学常数e
DOUBLE	pi()	Returns the value of pi. 数学常数pi
BIGINT	factorial(INT a)	Returns the factorial of a (as of Hive ). Valid a is [0..20]. 求a的阶乘
DOUBLE	cbrt(DOUBLE a)	Returns the cube root of a double value (as of Hive ). 求a的立方根
INT BIGINT	shiftleft(TINYINT|SMALLINT|INT a, INT b) shiftleft(BIGINT a, INT b)	Bitwise left shift (as of Hive ). Shifts a b positions to the left. Returns int for tinyint, smallint and int a. Returns bigint for bigint a. 按位左移
INT BIGINT	shiftright(TINYINT|SMALLINT|INT a, INTb) shiftright(BIGINT a, INT b)	Bitwise right shift (as of Hive ). Shifts a b positions to the right. Returns int for tinyint, smallint and int a. Returns bigint for bigint a. 按拉右移
INT BIGINT	shiftrightunsigned(TINYINT|SMALLINT|INTa, INT b), shiftrightunsigned(BIGINT a, INT b)	Bitwise unsigned right shift (as of Hive ). Shifts a b positions to the right. Returns int for tinyint, smallint and int a. Returns bigint for bigint a. 无符号按位右移（<<<）
T	greatest(T v1, T v2, ...)	Returns the greatest value of the list of values (as of Hive ). Fixed to return NULL when one or more arguments are NULL, and strict type restriction relaxed, consistent with ">" operator (as of Hive ). 求最大值
T	least(T v1, T v2, ...)	Returns the least value of the list of values (as of Hive ). Fixed to return NULL when one or more arguments are NULL, and strict type restriction relaxed, consistent with "<" operator (as of Hive ). 求最小值

 

集合函数

Return Type	Name(Signature)	Description
int	size(Map<K.V>)	Returns the number of elements in the map type. 求map的长度
int	size(Array<T>)	Returns the number of elements in the array type. 求数组的长度
array<K>	map_keys(Map<K.V>)	Returns an unordered array containing the keys of the input map. 返回map中的所有key
array<V>	map_values(Map<K.V>)	Returns an unordered array containing the values of the input map. 返回map中的所有value
boolean	array_contains(Array<T>, value)	Returns TRUE if the array contains value. 如该数组Array<T>包含value返回true。，否则返回false
array	sort_array(Array<T>)	Sorts the input array in ascending order according to the natural ordering of the array elements and returns it (as of version ). 按自然顺序对数组进行排序并返回

 

类型转换函数

Return Type	Name(Signature)	Description
binary	binary(string|binary)	Casts the parameter into a binary. 将输入的值转换成二进制
Expected "=" to follow "type"	cast(expr as <type>)	Converts the results of the expression expr to <type>. For example, cast('1' as BIGINT) will convert the string '1' to its integral representation. A null is returned if the conversion does not succeed. If cast(expr as boolean) Hive returns true for a non-empty string. 将expr转换成type类型 如：cast("1" as BIGINT) 将字符串1转换成了BIGINT类型，如果转换失败将返回NULL

 

 

日期函数

Return Type	Name(Signature)	Description
string	from_unixtime(bigint unixtime[, string format])	Converts the number of seconds from unix epoch (1970-01-01 00:00:00 UTC) to a string representing the timestamp of that moment in the current system time zone in the format of "1970-01-01 00:00:00". 将时间的秒值转换成format格式（format可为“yyyy-MM-dd hh:mm:ss”,“yyyy-MM-dd hh”,“yyyy-MM-dd hh:mm”等等）如from_unixtime(1250111000,"yyyy-MM-dd") 得到2009-03-12
bigint	unix_timestamp()	Gets current Unix timestamp in seconds. 获取本地时区下的时间戳
bigint	unix_timestamp(string date)	Converts time string in format yyyy-MM-dd HH:mm:ss to Unix timestamp (in seconds), using the default timezone and the default locale, return 0 if fail: unix_timestamp('2009-03-20 11:30:01') = 1237573801 将格式为yyyy-MM-dd HH:mm:ss的时间字符串转换成时间戳  如unix_timestamp('2009-03-20 11:30:01') = 1237573801
bigint	unix_timestamp(string date, string pattern)	Convert time string with given pattern (see []) to Unix time stamp (in seconds), return 0 if fail: unix_timestamp('2009-03-20', 'yyyy-MM-dd') = 1237532400. 将指定时间字符串格式字符串转换成Unix时间戳，如果格式不对返回0 如：unix_timestamp('2009-03-20', 'yyyy-MM-dd') = 1237532400
string	to_date(string timestamp)	Returns the date part of a timestamp string: to_date("1970-01-01 00:00:00") = "1970-01-01". 返回时间字符串的日期部分
int	year(string date)	Returns the year part of a date or a timestamp string: year("1970-01-01 00:00:00") = 1970, year("1970-01-01") = 1970. 返回时间字符串的年份部分
int	quarter(date/timestamp/string)	Returns the quarter of the year for a date, timestamp, or string in the range 1 to 4 (as of Hive ). Example: quarter('2015-04-08') = 2. 返回当前时间属性哪个季度 如quarter('2015-04-08') = 2
int	month(string date)	Returns the month part of a date or a timestamp string: month("1970-11-01 00:00:00") = 11, month("1970-11-01") = 11. 返回时间字符串的月份部分
int	day(string date) dayofmonth(date)	Returns the day part of a date or a timestamp string: day("1970-11-01 00:00:00") = 1, day("1970-11-01") = 1. 返回时间字符串的天
int	hour(string date)	Returns the hour of the timestamp: hour('2009-07-30 12:58:59') = 12, hour('12:58:59') = 12. 返回时间字符串的小时
int	minute(string date)	Returns the minute of the timestamp. 返回时间字符串的分钟
int	second(string date)	Returns the second of the timestamp. 返回时间字符串的秒
int	weekofyear(string date)	Returns the week number of a timestamp string: weekofyear("1970-11-01 00:00:00") = 44, weekofyear("1970-11-01") = 44. 返回时间字符串位于一年中的第几个周内  如weekofyear("1970-11-01 00:00:00") = 44, weekofyear("1970-11-01") = 44
int	datediff(string enddate, string startdate)	Returns the number of days from startdate to enddate: datediff('2009-03-01', '2009-02-27') = 2. 计算开始时间startdate到结束时间enddate相差的天数
string	date_add(string startdate, int days)	Adds a number of days to startdate: date_add('2008-12-31', 1) = '2009-01-01'. 从开始时间startdate加上days
string	date_sub(string startdate, int days)	Subtracts a number of days to startdate: date_sub('2008-12-31', 1) = '2008-12-30'. 从开始时间startdate减去days
timestamp	from_utc_timestamp(timestamp, string timezone)	Assumes given timestamp is UTC and converts to given timezone (as of Hive ). For example, from_utc_timestamp('1970-01-01 08:00:00','PST') returns 1970-01-01 00:00:00. 如果给定的时间戳并非UTC，则将其转化成指定的时区下时间戳
timestamp	to_utc_timestamp(timestamp, string timezone)	Assumes given timestamp is in given timezone and converts to UTC (as of Hive ). For example, to_utc_timestamp('1970-01-01 00:00:00','PST') returns 1970-01-01 08:00:00. 如果给定的时间戳指定的时区下时间戳，则将其转化成UTC下的时间戳
date	current_date	Returns the current date at the start of query evaluation (as of Hive ). All calls of current_date within the same query return the same value. 返回当前时间日期
timestamp	current_timestamp	Returns the current timestamp at the start of query evaluation (as of Hive ). All calls of current_timestamp within the same query return the same value. 返回当前时间戳
string	add_months(string start_date, int num_months)	Returns the date that is num_months after start_date (as of Hive ). start_date is a string, date or timestamp. num_months is an integer. The time part of start_date is ignored. If start_date is the last day of the month or if the resulting month has fewer days than the day component of start_date, then the result is the last day of the resulting month. Otherwise, the result has the same day component as start_date. 返回当前时间下再增加num_months个月的日期
string	last_day(string date)	Returns the last day of the month which the date belongs to (as of Hive ). date is a string in the format 'yyyy-MM-dd HH:mm:ss' or 'yyyy-MM-dd'. The time part of date is ignored. 返回这个月的最后一天的日期，忽略时分秒部分（HH:mm:ss）
string	next_day(string start_date, string day_of_week)	Returns the first date which is later than start_date and named as day_of_week (as of Hive). start_date is a string/date/timestamp. day_of_week is 2 letters, 3 letters or full name of the day of the week (e.g. Mo, tue, FRIDAY). The time part of start_date is ignored. Example: next_day('2015-01-14', 'TU') = 2015-01-20. 返回当前时间的下一个星期X所对应的日期 如：next_day('2015-01-14', 'TU') = 2015-01-20  以2015-01-14为开始时间，其下一个星期二所对应的日期为2015-01-20
string	trunc(string date, string format)	Returns date truncated to the unit specified by the format (as of Hive ). Supported formats: MONTH/MON/MM, YEAR/YYYY/YY. Example: trunc('2015-03-17', 'MM') = 2015-03-01. 返回时间的最开始年份或月份  如trunc("2016-06-26",“MM”)=2016-06-01  trunc("2016-06-26",“YY”)=2016-01-01   注意所支持的格式为MONTH/MON/MM, YEAR/YYYY/YY
double	months_between(date1, date2)	Returns number of months between dates date1 and date2 (as of Hive ). If date1 is later than date2, then the result is positive. If date1 is earlier than date2, then the result is negative. If date1 and date2 are either the same days of the month or both last days of months, then the result is always an integer. Otherwise the UDF calculates the fractional portion of the result based on a 31-day month and considers the difference in time components date1 and date2. date1 and date2 type can be date, timestamp or string in the format 'yyyy-MM-dd' or 'yyyy-MM-dd HH:mm:ss'. The result is rounded to 8 decimal places. Example: months_between('1997-02-28 10:30:00', '1996-10-30') = 3.94959677 返回date1与date2之间相差的月份，如date1>date2，则返回正，如果date1<date2,则返回负，否则返回0.0  如：months_between('1997-02-28 10:30:00', '1996-10-30') = 3.94959677  1997-02-28 10:30:00与1996-10-30相差3.94959677个月
string	date_format(date/timestamp/string ts, string fmt)	Converts a date/timestamp/string to a value of string in the format specified by the date format fmt (as of Hive ). Supported formats are Java SimpleDateFormat formats –. The second argument fmt should be constant. Example: date_format('2015-04-08', 'y') = '2015'. date_format can be used to implement other UDFs, e.g.: dayname(date) is date_format(date, 'EEEE') dayofyear(date) is date_format(date, 'D') 按指定格式返回时间date 如：date_format("2016-06-22","MM-dd")=06-22

 

 

条件函数

Return Type	Name(Signature)	Description
T	if(boolean testCondition, T valueTrue, T valueFalseOrNull)	Returns valueTrue when testCondition is true, returns valueFalseOrNull otherwise. 如果testCondition 为true就返回valueTrue,否则返回valueFalseOrNull ，（valueTrue，valueFalseOrNull为泛型）
T	nvl(T value, T default_value)	Returns default value if value is null else returns value (as of HIve ). 如果value值为NULL就返回default_value,否则返回value
T	COALESCE(T v1, T v2, ...)	Returns the first v that is not NULL, or NULL if all v's are NULL. 返回第一非null的值，如果全部都为NULL就返回NULL  如：COALESCE (NULL,44,55)=44/strong>
T	CASE a WHEN b THEN c [WHEN d THEN e]* [ELSE f] END	When a = b, returns c; when a = d, returns e; else returns f. 如果a=b就返回c,a=d就返回e，否则返回f  如CASE 4 WHEN 5  THEN 5 WHEN 4 THEN 4 ELSE 3 END 将返回4
T	CASE WHEN a THEN b [WHEN c THEN d]* [ELSE e] END	When a = true, returns b; when c = true, returns d; else returns e. 如果a=ture就返回b,c= ture就返回d，否则返回e  如：CASE WHEN  5>0  THEN 5 WHEN 4>0 THEN 4 ELSE 0 END 将返回5；CASE WHEN  5<0  THEN 5 WHEN 4<0 THEN 4 ELSE 0 END 将返回0
boolean	isnull( a )	Returns true if a is NULL and false otherwise. 如果a为null就返回true，否则返回false
boolean	isnotnull ( a )	Returns true if a is not NULL and false otherwise. 如果a为非null就返回true，否则返回false

 

 

字符函数

Return Type	Name(Signature)	Description
int	ascii(string str)	Returns the numeric value of the first  character of str. 返回str中首个ASCII字符串的整数值
string	base64(binary bin)	Converts the argument from binary to a base 64 string (as of Hive ).. 将二进制bin转换成64位的字符串
string	concat(string|binary A, string|binary B...)	Returns the string or bytes resulting from concatenating the strings or bytes passed in as parameters in order. For example, concat('foo', 'bar') results in 'foobar'. Note that this function can take any number of input strings.. 对二进制字节码或字符串按次序进行拼接
array<struct<string,double>>	context_ngrams(array<array<string>>, array<string>, int K, int pf)	Returns the top-k contextual N-grams from a set of tokenized sentences, given a string of "context". See  for more information.. 与ngram类似，但context_ngram()允许你预算指定上下文(数组)来去查找子序列，具体看(这里的解释更易懂)
string	concat_ws(string SEP, string A, string B...)	Like concat() above, but with custom separator SEP.. 与concat()类似，但使用指定的分隔符喜进行分隔
string	concat_ws(string SEP, array<string>)	Like concat_ws() above, but taking an array of strings. (as of Hive ). 拼接Array中的元素并用指定分隔符进行分隔
string	decode(binary bin, string charset)	Decodes the first argument into a String using the provided character set (one of 'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'). If either argument is null, the result will also be null. (As of Hive .). 使用指定的字符集charset将二进制值bin解码成字符串，支持的字符集有：'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'，如果任意输入参数为NULL都将返回NULL
binary	encode(string src, string charset)	Encodes the first argument into a BINARY using the provided character set (one of 'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'). If either argument is null, the result will also be null. (As of Hive .). 使用指定的字符集charset将字符串编码成二进制值，支持的字符集有：'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'，如果任一输入参数为NULL都将返回NULL
int	find_in_set(string str, string strList)	Returns the first occurance of str in strList where strList is a comma-delimited string. Returns null if either argument is null. Returns 0 if the first argument contains any commas. For example, find_in_set('ab', 'abc,b,ab,c,def') returns 3.. 返回以逗号分隔的字符串中str出现的位置，如果参数str为逗号或查找失败将返回0，如果任一参数为NULL将返回NULL回
string	format_number(number x, int d)	Formats the number X to a format like '#,###,###.##', rounded to D decimal places, and returns the result as a string. If D is 0, the result has no decimal point or fractional part. (As of Hive ; bug with float types fixed in , decimal type support added in ). 将数值X转换成"#,###,###.##"格式字符串，并保留d位小数，如果d为0，将进行四舍五入且不保留小数
string	get_json_object(string json_string, string path)	Extracts json object from a json string based on json path specified, and returns json string of the extracted json object. It will return null if the input json string is invalid. NOTE: The json path can only have the characters [0-9a-z_], i.e., no upper-case or special characters. Also, the keys *cannot start with numbers.* This is due to restrictions on Hive column names.. 从指定路径上的JSON字符串抽取出JSON对象，并返回这个对象的JSON格式，如果输入的JSON是非法的将返回NULL,注意此路径上JSON字符串只能由数字 字母 下划线组成且不能有大写字母和特殊字符，且key不能由数字开头，这是由于Hive对列名的限制
boolean	in_file(string str, string filename)	Returns true if the string str appears as an entire line in filename.. 如果文件名为filename的文件中有一行数据与字符串str匹配成功就返回true
int	instr(string str, string substr)	Returns the position of the first occurrence of substr in str. Returns null if either of the arguments are null and returns 0 if substr could not be found in str. Be aware that this is not zero based. The first character in str has index 1.. 查找字符串str中子字符串substr出现的位置，如果查找失败将返回0，如果任一参数为Null将返回null，注意位置为从1开始的
int	length(string A)	Returns the length of the string.. 返回字符串的长度
int	locate(string substr, string str[, int pos])	Returns the position of the first occurrence of substr in str after position pos.. 查找字符串str中的pos位置后字符串substr第一次出现的位置
string	lower(string A) lcase(string A)	Returns the string resulting from converting all characters of B to lower case. For example, lower('fOoBaR') results in 'foobar'.. 将字符串A的所有字母转换成小写字母
string	lpad(string str, int len, string pad)	Returns str, left-padded with pad to a length of len.. 从左边开始对字符串str使用字符串pad填充，最终len长度为止，如果字符串str本身长度比len大的话，将去掉多余的部分
string	ltrim(string A)	Returns the string resulting from trimming spaces from the beginning(left hand side) of A. For example, ltrim(' foobar ') results in 'foobar '.. 去掉字符串A前面的空格
array<struct<string,double>>	ngrams(array<array<string>>, int N, int K, int pf)	Returns the top-k N-grams from a set of tokenized sentences, such as those returned by the sentences() UDAF. See  for more information.. 返回出现次数TOP K的的子序列,n表示子序列的长度，具体看 (这里的解释更易懂)
string	parse_url(string urlString, string partToExtract [, string keyToExtract])	Returns the specified part from the URL. Valid values for partToExtract include HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, and USERINFO. For example, parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'HOST') returns 'facebook.com'. Also a value of a particular key in QUERY can be extracted by providing the key as the third argument, for example, parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'QUERY', 'k1') returns 'v1'.. 返回从URL中抽取指定部分的内容，参数url是URL字符串，而参数partToExtract是要抽取的部分，这个参数包含(HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, and USERINFO,例如：parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'HOST') ='facebook.com'，如果参数partToExtract值为QUERY则必须指定第三个参数key  如：parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'QUERY', 'k1') =‘v1’
string	printf(String format, Obj... args)	Returns the input formatted according do printf-style format strings (as of Hive).. 按照printf风格格式输出字符串
string	regexp_extract(string subject, string pattern, int index)	Returns the string extracted using the pattern. For example, regexp_extract('foothebar', 'foo(.*?)(bar)', 2) returns 'bar.' Note that some care is necessary in using predefined character classes: using '\s' as the second argument will match the letter s; '\\s' is necessary to match whitespace, etc. The 'index' parameter is the Java regex Matcher group() method index. See docs/api/java/util/regex/Matcher.html for more information on the 'index' or Java regex group() method.. 抽取字符串subject中符合正则表达式pattern的第index个部分的子字符串，注意些预定义字符的使用，如第二个参数如果使用'\s'将被匹配到s,'\\s'才是匹配空格
string	regexp_replace(string INITIAL_STRING, string PATTERN, string REPLACEMENT)	Returns the string resulting from replacing all substrings in INITIAL_STRING that match the java regular expression syntax defined in PATTERN with instances of REPLACEMENT. For example, regexp_replace("foobar", "oo|ar", "") returns 'fb.' Note that some care is necessary in using predefined character classes: using '\s' as the second argument will match the letter s; '\\s' is necessary to match whitespace, etc.. 按照Java正则表达式PATTERN将字符串INTIAL_STRING中符合条件的部分成REPLACEMENT所指定的字符串，如里REPLACEMENT这空的话，抽符合正则的部分将被去掉  如：regexp_replace("foobar", "oo|ar", "") = 'fb.' 注意些预定义字符的使用，如第二个参数如果使用'\s'将被匹配到s,'\\s'才是匹配空格
string	repeat(string str, int n)	Repeats str n times.. 重复输出n次字符串str
string	reverse(string A)	Returns the reversed string.. 反转字符串
string	rpad(string str, int len, string pad)	Returns str, right-padded with pad to a length of len.. 从右边开始对字符串str使用字符串pad填充，最终len长度为止，如果字符串str本身长度比len大的话，将去掉多余的部分
string	rtrim(string A)	Returns the string resulting from trimming spaces from the end(right hand side) of A. For example, rtrim(' foobar ') results in ' foobar'.. 去掉字符串后面出现的空格
array<array<string>>	sentences(string str, string lang, string locale)	Tokenizes a string of natural language text into words and sentences, where each sentence is broken at the appropriate sentence boundary and returned as an array of words. The 'lang' and 'locale' are optional arguments. For example, sentences('Hello there! How are you?') returns ( ("Hello", "there"), ("How", "are", "you") ).. 字符串str将被转换成单词数组，如：sentences('Hello there! How are you?') =( ("Hello", "there"), ("How", "are", "you") )
string	space(int n)	Returns a string of n spaces.. 返回n个空格
array	split(string str, string pat)	Splits str around pat (pat is a regular expression).. 按照正则表达式pat来分割字符串str,并将分割后的数组字符串的形式返回
map<string,string>	str_to_map(text[, delimiter1, delimiter2])	Splits text into key-value pairs using two delimiters. Delimiter1 separates text into K-V pairs, and Delimiter2 splits each K-V pair. Default delimiters are ',' for delimiter1 and '=' for delimiter2.. 将字符串str按照指定分隔符转换成Map，第一个参数是需要转换字符串，第二个参数是键值对之间的分隔符，默认为逗号;第三个参数是键值之间的分隔符，默认为"="
string	substr(string|binary A, int start) substring(string|binary A, int start)	Returns the substring or slice of the byte array of A starting from start position till the end of string A. For example, substr('foobar', 4) results in 'bar' (see []).. 对于字符串A,从start位置开始截取字符串并返回
string	substr(string|binary A, int start, int len) substring(string|binary A, int start, int len)	Returns the substring or slice of the byte array of A starting from start position with length len. For example, substr('foobar', 4, 1) results in 'b' (see []).. 对于二进制/字符串A,从start位置开始截取长度为length的字符串并返回
string	substring_index(string A, string delim, int count)	Returns the substring from string A before count occurrences of the delimiter delim (as of Hive ). If count is positive, everything to the left of the final delimiter (counting from the left) is returned. If count is negative, everything to the right of the final delimiter (counting from the right) is returned. Substring_index performs a case-sensitive match when searching for delim. Example: substring_index('www.apache.org', '.', 2) = 'www.apache'.. 截取第count分隔符之前的字符串，如count为正则从左边开始截取，如果为负则从右边开始截取
string	translate(string|char|varchar input, string|char|varchar from, string|char|varchar to)	Translates the input string by replacing the characters present in the from string with the corresponding characters in the to string. This is similar to the translatefunction in . If any of the parameters to this UDF are NULL, the result is NULL as well. (Available as of Hive , for string types) Char/varchar support added as of .. 将input出现在from中的字符串替换成to中的字符串 如：translate("MOBIN","BIN","M")="MOM"
string	trim(string A)	Returns the string resulting from trimming spaces from both ends of A. For example, trim(' foobar ') results in 'foobar'. 将字符串A前后出现的空格去掉
binary	unbase64(string str)	Converts the argument from a base 64 string to BINARY. (As of Hive .). 将64位的字符串转换二进制值
string	upper(string A) ucase(string A)	Returns the string resulting from converting all characters of A to upper case. For example, upper('fOoBaR') results in 'FOOBAR'.. 将字符串A中的字母转换成大写字母
string	initcap(string A)	Returns string, with the first letter of each word in uppercase, all other letters in lowercase. Words are delimited by whitespace. (As of Hive .). 将字符串A转换第一个字母大写其余字母的字符串
int	levenshtein(string A, string B)	Returns the Levenshtein distance between two strings (as of Hive ). For example, levenshtein('kitten', 'sitting') results in 3.. 计算两个字符串之间的差异大小  如：levenshtein('kitten', 'sitting') = 3
string	soundex(string A)	Returns soundex code of the string (as of Hive ). For example, soundex('Miller') results in M460.. 将普通字符串转换成soundex字符串

 

 

聚合函数

Return Type	Name(Signature)	Description
BIGINT	count(*), count(expr), count(DISTINCT expr[, expr...])	count(*) - Returns the total number of retrieved rows, including rows containing NULL values. 统计总行数，包括含有NULL值的行 count(expr) - Returns the number of rows for which the supplied expression is non-NULL. 统计提供非NULL的expr表达式值的行数 count(DISTINCT expr[, expr]) - Returns the number of rows for which the supplied expression(s) are unique and non-NULL. Execution of this can be optimized with . 统计提供非NULL且去重后的expr表达式值的行数
DOUBLE	sum(col), sum(DISTINCT col)	Returns the sum of the elements in the group or the sum of the distinct values of the column in the group. sum(col),表示求指定列的和，sum(DISTINCT col)表示求去重后的列的和
DOUBLE	avg(col), avg(DISTINCT col)	Returns the average of the elements in the group or the average of the distinct values of the column in the group. avg(col),表示求指定列的平均值，avg(DISTINCT col)表示求去重后的列的平均值
DOUBLE	min(col)	Returns the minimum of the column in the group. 求指定列的最小值
DOUBLE	max(col)	Returns the maximum value of the column in the group. 求指定列的最大值
DOUBLE	variance(col), var_pop(col)	Returns the variance of a numeric column in the group. 求指定列数值的方差
DOUBLE	var_samp(col)	Returns the unbiased sample variance of a numeric column in the group. 求指定列数值的样本方差
DOUBLE	stddev_pop(col)	Returns the standard deviation of a numeric column in the group. 求指定列数值的标准偏差
DOUBLE	stddev_samp(col)	Returns the unbiased sample standard deviation of a numeric column in the group. 求指定列数值的样本标准偏差
DOUBLE	covar_pop(col1, col2)	Returns the population covariance of a pair of numeric columns in the group. 求指定列数值的协方差
DOUBLE	covar_samp(col1, col2)	Returns the sample covariance of a pair of a numeric columns in the group. 求指定列数值的样本协方差
DOUBLE	corr(col1, col2)	Returns the Pearson coefficient of correlation of a pair of a numeric columns in the group. 返回两列数值的相关系数
DOUBLE	percentile(BIGINT col, p)	Returns the exact pth percentile of a column in the group (does not work with floating point types). p must be between 0 and 1. NOTE: A true percentile can only be computed for integer values. Use PERCENTILE_APPROX if your input is non-integral. 返回col的p%分位数

 

 

表生成函数

Return Type	Name(Signature)	Description
Array Type	explode(array<TYPE> a)	For each element in a, generates a row containing that element. 对于a中的每个元素，将生成一行且包含该元素
N rows	explode(ARRAY)	Returns one row for each element from the array.. 每行对应数组中的一个元素
N rows	explode(MAP)	Returns one row for each key-value pair from the input map with two columns in each row: one for the key and another for the value. (As of Hive .). 每行对应每个map键-值，其中一个字段是map的键，另一个字段是map的值
N rows	posexplode(ARRAY)	Behaves like explode for arrays, but includes the position of items in the original array by returning a tuple of (pos, value). (As of .). 与explode类似，不同的是还返回各元素在数组中的位置
N rows	stack(INT n, v_1, v_2, ..., v_k)	Breaks up v_1, ..., v_k into n rows. Each row will have k/n columns. n must be constant.. 把M列转换成N行，每行有M/N个字段，其中n必须是个常数
tuple	json_tuple(jsonStr, k1, k2, ...)	Takes a set of names (keys) and a JSON string, and returns a tuple of values. This is a more efficient version of the get_json_object UDF because it can get multiple keys with just one call.. 从一个JSON字符串中获取多个键并作为一个元组返回，与get_json_object不同的是此函数能一次获取多个键值
tuple	parse_url_tuple(url, p1, p2, ...)	This is similar to the parse_url() UDF but can extract multiple parts at once out of a URL. Valid part names are: HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, USERINFO, QUERY:<KEY>.. 返回从URL中抽取指定N部分的内容，参数url是URL字符串，而参数p1,p2,....是要抽取的部分，这个参数包含HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, USERINFO, QUERY:<KEY>
	inline(ARRAY<STRUCT[,STRUCT]>)	Explodes an array of structs into a table. (As of Hive .). 将结构体数组提取出来并插入到表中

 

 

 

参考资料

《Hive权威指南》

 

聚合函数

hive函数的分类

hive的客户端

显示当前会话有多少函数可用

SHOW FUNCTIONS;

如：

hive> show functions ;

OK ! != %

 

显示函数的描述信息

DESC FUNCTION concat;

如：

hive> DESC FUNCTION concat;

OK concat(str1, str2, ... strN) - returns the concatenation of str1, str2, ... strN or concat(bin1, bin2, ... binN) - returns the concatenation of bytes in binary data  bin1, bin2, ... binN Time taken: 0.005 seconds, Fetched: 1 row(s)

 

显示函数的扩展描述信息

DESC FUNCTION EXTENDED concat;

一.简单函数

1.数学函数

 返回对a四舍五入的BIGINT值

 

1 返回值：2 hive> select round(2.5);3 OK4 3.05 Time taken: 0.093 seconds, Fetched: 1 row(s)

 

返回DOUBLE型d的保留n位小数的DOUBLW型的近似值 round(DOUBLE a, INT d)

 

1 返回值：double2 hive> select round(0.5002,2);3 OK4 0.55 Time taken: 0.074 seconds, Fetched: 1 row(s)

 

银行家舍入法（1~4：舍，6~9：进，5->前位数是偶：舍，5->前位数是奇：进） bround(DOUBLE a)

返回值：doublebround(2.5) = 2, bround(3.5) = 4.

银行家舍入法,保留d位小数 bround(DOUBLE a, INT d)

1 返回值：double2 bround(8.25, 1) = 8.2, bround(8.35, 1) = 8.4

向下取整，最数轴上最接近要求的值的左边的值  如：6.10->6   -3.4->-4 floor(DOUBLE a)

1 返回值：double2 hive> select floor(6.10);3 OK4 65 Time taken: 0.07 seconds, Fetched: 1 row(s)6 hive> select floor(-3.4);7 OK8 -49 Time taken: 0.104 seconds, Fetched: 1 row(s)

求其不小于小给定实数的最小整数如：ceil(6) = ceil(6.1)= ceil(6.9) = 6 ceil(DOUBLE a), ceiling(DOUBLE a)

1 返回值：BIGINT 2 hive> select ceil(6); 3 OK 4 6 5 Time taken: 0.2 seconds, Fetched: 1 row(s) 6 hive> select ceil(6.1); 7 OK 8 7 9 Time taken: 0.061 seconds, Fetched: 1 row(s)10 hive> select ceil(6.9);11 OK12 713 Time taken: 0.153 seconds, Fetched: 1 row(s)

每行返回一个DOUBLE型随机数seed是随机因子 rand(), rand(INT seed)

1 返回值：DOUBLE2 hive> select rand(2);3 OK4 0.73114693601990585 Time taken: 0.068 seconds, Fetched: 1 row(s)6 hive> select rand();7 OK8 0.78590714910959239 Time taken: 0.064 seconds, Fetched: 1 row(s)

返回e的a幂次方， a可为小数 exp(DOUBLE a), exp(DECIMAL a)

1 返回值：double2 hive> select exp(2);3 OK4 7.389056098930655 Time taken: 0.1 seconds, Fetched: 1 row(s)

 以自然数为底d的对数，a可为小数 ln(DOUBLE a), ln(DECIMAL a)

1 返回值：double 2 ln(DOUBLE a), ln(DECIMAL a) 3    > select ln(3); 4 OK 5 1.0986122886681098 6 Time taken: 0.081 seconds, Fetched: 1 row(s) 7 hive> select ln(3.2); 8 OK 9 1.163150809805680910 Time taken: 0.067 seconds, Fetched: 1 row(s)

以10为底d的对数，a可为小数 log10(DOUBLE a), log10(DECIMAL a)

1 返回值：double2 hive> select log10(3.2);3 OK4 0.5051499783199065 Time taken: 0.084 seconds, Fetched: 1 row(s)6 hive> select log10(3);7 OK8 0.477121254719662449 Time taken: 0.075 seconds, Fetched: 1 row(s)

 以2为底数d的对数，a可为小数  log2(DOUBLE a), log2(DECIMAL a)

1 返回值：double 2 hive>  3     > select log2(3); 4 OK 5 1.5849625007211563 6 Time taken: 0.083 seconds, Fetched: 1 row(s) 7 hive> select log2(3.2); 8 OK 9 1.678071905112637810 Time taken: 0.07 seconds, Fetched: 1 row(s)

以base为底的对数，base 与 a都是DOUBLE类型

log(DOUBLE base, DOUBLE a)

log(DECIMAL base, DECIMAL a)

1 返回值：double2 hive> select log(2,3.2);3 OK4 1.67807190511263785 Time taken: 0.084 seconds, Fetched: 1 row(s)6 hive> select log(2,3);7 OK8 1.58496250072115639 Time taken: 0.066 seconds, Fetched: 1 row(s)

计算a的p次幂 pow(DOUBLE a, DOUBLE p), power(DOUBLE a, DOUBLE p)

1 返回值:double2 hive> select pow(2,4);3 OK4 16.05 Time taken: 0.065 seconds, Fetched: 1 row(s)

计算a的平方根 sqrt(DOUBLE a), sqrt(DECIMAL a)

1 返回值：double2 select sqrt(2);

计算二进制a的STRING类型，a为BIGINT类型 bin(BIGINT a)

返回值：stringhive> select bin(2);OK10Time taken: 0.194 seconds, Fetched: 1 row(s)

计算十六进制a的STRING类型，如果a为STRING类型就转换成字符相对应的十六进制 hex(BIGINT a) hex(STRING a) hex(BINARY a)

1 返回值：STRING2 hive> select hex(2);3 OK4 25 Time taken: 0.097 seconds, Fetched: 1 row(s)

hex的逆方法

unhex(STRING a)

1 返回值：BINARY2 hive> select unhex(2);3 OK4  5 Time taken: 0.077 seconds, Fetched: 1 row(s)

将GIGINT/STRING类型的num从from_base进制转换成to_base进制 conv(BIGINT num, INT from_base, INT to_base), conv(STRING num, INT from_base, INT to_base)

1 返回值：STRING2 hive> select conv(2,10,2);3 OK4 105 Time taken: 0.075 seconds, Fetched: 1 row(s)

计算a的绝对值 abs(DOUBLE a)

1 返回值：DOUBLE2 hive> select abs(-2);3 OK4 25 Time taken: 0.077 seconds, Fetched: 1 row(s)

a对b取模 pmod(INT a, INT b), pmod(DOUBLE a, DOUBLE b)

1 返回值：double2 hive> select pmod(4,2);3 OK4 05 Time taken: 0.077 seconds, Fetched: 1 row(s)

求a的正弦值 sin(DOUBLE a), sin(DECIMAL a)

1 返回值：double2 hive> select sin(2.5);3 OK4 0.59847214410395645 Time taken: 0.092 seconds, Fetched: 1 row(s)

求d的反正弦值 asin(DOUBLE a), asin(DECIMAL a)

1 返回值：double2 hive> select asin(2.5);3 OK4 NaN5 Time taken: 0.097 seconds, Fetched: 1 row(s)

求余弦值 cos(DOUBLE a), cos(DECIMAL a)

1 返回值：double2 hive> select cos(2.5);3 OK4 -0.80114361554693375 Time taken: 0.087 seconds, Fetched: 1 row(s)

求反余弦值 acos(DOUBLE a), acos(DECIMAL a)

1 返回值：double2 hive> select acos(2.5);3 OK4 NaN5 Time taken: 0.091 seconds, Fetched: 1 row(s)

求正切值 tan(DOUBLE a), tan(DECIMAL a)

1 返回值：double2 hive> select tan(2.5);3 OK4 -0.74702229723866035 Time taken: 0.076 seconds, Fetched: 1 row(s)

求反正切值 atan(DOUBLE a), atan(DECIMAL a)

1 返回值：double2 hive> select atan(2.5);3 OK4 1.19028994968253175 Time taken: 0.074 seconds, Fetched: 1 row(s)

奖弧度值转换角度值 degrees(DOUBLE a), degrees(DECIMAL a)

1 返回值：DOUBLE2 hive> select degrees(30);3 OK4 1718.87338539246985 Time taken: 0.114 seconds, Fetched: 1 row(s)

将角度值转换成弧度值 radians(DOUBLE a), radians(DOUBLE a)

1 返回值：double2 hive> select radians(30);3 OK4 0.52359877559829885 Time taken: 0.093 seconds, Fetched: 1 row(s)

返回a positive(INT a), positive(DOUBLE a)

1 返回值：INT or DOUBLE2 hive> select positive(2);3 OK4 25 Time taken: 0.124 seconds, Fetched: 1 row(s)

返回a的相反数 negative(INT a), negative(DOUBLE a)

1 返回值：double2 hive> select negative(2);3 OK4 -25 Time taken: 0.066 seconds, Fetched: 1 row(s)

如果a是正数则返回1.0，是负数则返回-1.0，否则返回0.0 sign(DOUBLE a), sign(DECIMAL a)

1 返回值：DOUBLE or INT2 hive> select sign(2);3 OK4 1.05 Time taken: 0.091 seconds, Fetched: 1 row(s)

数学常数e e()

1 返回值：double2 hive> select e();3 OK4 2.7182818284590455 Time taken: 0.07 seconds, Fetched: 1 row(s)

数学常数pi pi()

1 返回值：double2 hive> select pi();3 OK4 3.1415926535897935 Time taken: 0.082 seconds, Fetched: 1 row(s)

求a的阶乘 factorial(INT a)

1 返回值：BIGINT2 select  factorial(2);

求a的立方根 cbrt(DOUBLE a)

1 返回值：DOUBLE2 select cbrt(2);

按位左移

shiftleft(TINYINT|SMALLINT|INT a, INT b)

shiftleft(BIGINT a, INT b)

1 返回值：int bigint2 hive> select shiftleft(2,3);

按拉右移

shiftright(TINYINT|SMALLINT|INT a, INTb)

shiftright(BIGINT a, INT b)

1 返回值：INT BIGINT2 hive> select shiftrigth(2,3);

无符号按位右移（<<<）

shiftrightunsigned(TINYINT|SMALLINT|INTa, INT b),

shiftrightunsigned(BIGINT a, INT b)

1 返回值：INT BIGINT2 select shiftrightunsigned(2,3);

求最大值 greatest(T v1, T v2, ...)

1 返回值：T2 hive> select greatest(2,3,6,7);3 OK4 75 Time taken: 0.072 seconds, Fetched: 1 row(s)

求最小值 least(T v1, T v2, ...)

1 返回值：double2 hive> select least(2,3,6,7);3 OK4 25 Time taken: 0.079 seconds, Fetched: 1 row(s)

 

2.类型转换函数

 将输入的值转换成二进制  binary(string|binary)

1 返回值：binary2 hive> select binary('4');3 OK4 45 Time taken: 0.08 seconds, Fetched: 1 row(s)

将expr转换成type类型 如：cast("1" as BIGINT) 将字符串1转换成了BIGINT类型，如果转换失败将返回NULL cast(expr as <type>)

1 返回值：Expected "=" to follow "type"2 hive> select cast("1" as BIGINT) ;3 OK4 15 Time taken: 0.266 seconds, Fetched: 1 row(s)

3.日期函数

 日期函数UNIX时间戳转日期函数: from_unixtime语法:   from_unixtime(bigint unixtime[, string format])

1 返回值: string2 说明: 转化UNIX时间戳（从1970-01-01 00:00:00 UTC到指定时间的秒数）到当前时区的时间格式3 举例：4 hive> select from_unixtime(1323308943,'yyyyMMdd');5 OK6 201112087 Time taken: 0.152 seconds, Fetched: 1 row(s)

获取当前UNIX时间戳函数: unix_timestamp语法:   unix_timestamp()

1 返回值:   bigint2 说明: 获得当前时区的UNIX时间戳3 举例：4 Time taken: 0.152 seconds, Fetched: 1 row(s)5 hive>  select unix_timestamp();6 OK7 14879318718 Time taken: 0.106 seconds, Fetched: 1 row(s)

日期转UNIX时间戳函数: unix_timestamp语法:   unix_timestamp(string date)

1 返回值:   bigint2 说明: 转换格式为“yyyy-MM-dd HH:mm:ss“的日期到UNIX时间戳。如果转化失败，则返回0。3 举例：4 hive> select unix_timestamp('2011-12-07 13:01:03');5 OK6 13232340637 Time taken: 0.083 seconds, Fetched: 1 row(s)

指定格式日期转UNIX时间戳函数: unix_timestamp语法:   unix_timestamp(string date, string pattern)

1 返回值:   bigint2 说明: 转换pattern格式的日期到UNIX时间戳。如果转化失败，则返回0。3 举例：4 hive> select unix_timestamp('20111207 13:01:03','yyyyMMdd HH:mm:ss');5 OK6 13232340637 Time taken: 0.079 seconds, Fetched: 1 row(s)

日期时间转日期函数: to_date语法:   to_date(string timestamp)

1 返回值:   string2 说明: 返回日期时间字段中的日期部分。3 举例：4 hive> select to_date('2011-12-08 10:03:01') ;5 OK6 2011-12-087 Time taken: 0.194 seconds, Fetched: 1 row(s)

日期转年函数: year语法:   year(string date)

1 返回值: int2 说明: 返回日期中的年。3 举例：4 hive>  select year('2011-12-08 10:03:01');5 OK6 20117 Time taken: 0.168 seconds, Fetched: 1 row(s)

日期转月函数: month语法: month   (string date)

1 返回值: int2 说明: 返回日期中的月份。3 举例：4 hive>  select month('2011-12-08 10:03:01');5 OK6 127 Time taken: 0.084 seconds, Fetched: 1 row(s)

1 hive> select month('2011-08-08');2 OK3 84 Time taken: 0.095 seconds, Fetched: 1 row(s)

日期转天函数: day语法: day   (string date)

1 返回值: int2 说明: 返回日期中的天。3 举例：4 hive>  select day('2011-12-08 10:03:01');5 OK6 87 Time taken: 0.115 seconds, Fetched: 1 row(s)

1 hive> select day('2011-12-24');2 OK3 244 Time taken: 0.294 seconds, Fetched: 1 row(s)

日期转小时函数: hour语法: hour   (string date)

1 返回值: int2 说明: 返回日期中的小时。3 举例：4 hive> select hour('2011-12-08 10:03:01');5 OK6 107 Time taken: 0.082 seconds, Fetched: 1 row(s)

日期转分钟函数: minute语法: minute   (string date)

1 返回值: int2 说明: 返回日期中的分钟。3 举例：4 hive>  select minute('2011-12-08 10:03:01');5 OK6 37 Time taken: 0.181 seconds, Fetched: 1 row(s)

日期转秒函数: second语法: second   (string date)

1 返回值: int2 说明: 返回日期中的秒。3 举例：4 hive>  select second('2011-12-08 10:03:01');5 OK6 17 Time taken: 0.693 seconds, Fetched: 1 row(s)

日期转周函数: weekofyear语法:   weekofyear (string date)

1 返回值: int2 说明: 返回日期在当前的周数。3 举例：4 hive> select weekofyear('2011-12-08 10:03:01')5     > ;6 OK7 498 Time taken: 0.119 seconds, Fetched: 1 row(s)

日期比较函数: datediff语法:   datediff(string enddate, string startdate)

1 返回值: int2 说明: 返回结束日期减去开始日期的天数。3 举例：4 hive> select datediff('2012-12-08','2012-05-09');5 OK6 2137 Time taken: 0.082 seconds, Fetched: 1 row(s)

日期增加函数: date_add语法:   date_add(string startdate, int days)

1 返回值: string2 说明: 返回开始日期startdate增加days天后的日期。3 举例：4 hive> select date_add('2012-12-08',10);5 OK6 2012-12-187 Time taken: 0.201 seconds, Fetched: 1 row(s)

日期减少函数: date_sub语法:   date_sub (string startdate, int days)

1 返回值: string2 说明: 返回开始日期startdate减少days天后的日期。3 举例：4 hive> select date_sub('2012-12-08',10);5 OK6 2012-11-287 Time taken: 0.125 seconds, Fetched: 1 row(s)

返回这个月的最后一天的日期，忽略时分秒部分（HH:mm:ss） last_day(string date)

1 返回值：string2 hive> select  last_day('2017-02-17 08:34:23');3 OK4 2017-02-285 Time taken: 0.082 seconds, Fetched: 1 row(s)

返回当前时间的下一个星期X所对应的日期 如：next_day('2015-01-14', 'TU') = 2015-01-20  以2015-01-14为开始时间，其下一个星期二所对应的日期为2015-01-20

1 返回值：string2 hive> select next_day('2015-01-14', 'TU') ;3 OK4 2015-01-205 Time taken: 0.319 seconds, Fetched: 1 row(s)

返回当前时间属性哪个季度 如quarter('2015-04-08') = 2

1 返回值：int2 quarter(date/timestamp/string)

返回当前时间日期

返回值：datehive> select current_date;OK2017-02-25Time taken: 0.087 seconds, Fetched: 1 row(s)

如果给定的时间戳并非UTC，则将其转化成指定的时区下时间戳

1 返回值：timestamp2 from_utc_timestamp(timestamp, string timezone)3 hive> select from_utc_timestamp('1970-01-01 08:00:00','PST');4 OK5 1970-01-01 00:00:006 Time taken: 0.122 seconds, Fetched: 1 row(s)

如果给定的时间戳指定的时区下时间戳，则将其转化成UTC下的时间戳 to_utc_timestamp(timestamp, string timezone)

1 返回值：timestamp2 hive> select to_utc_timestamp('1970-01-01 00:00:00','PST');3 OK4 1970-01-01 08:00:005 Time taken: 0.099 seconds, Fetched: 1 row(s)

返回当前时间戳

1 返回值：timestamp2 hive> select current_timestamp;3 OK4 2017-02-25 00:28:46.7245 Time taken: 0.069 seconds, Fetched: 1 row(s)

返回当前时间下再增加num_months个月的日期  add_months(string start_date, int num_months)

1 返回值：string2 hive> select add_months('2017-02-10', 2);3 OK4 2017-04-105 Time taken: 0.061 seconds, Fetched: 1 row(s)

 

5.条件函数

 如果testCondition 为true就返回valueTrue,否则返回valueFalseOrNull ，（valueTrue，valueFalseOrNull为泛型）

if(boolean testCondition, T valueTrue, T valueFalseOrNull)

1 返回值：T

如果value值为NULL就返回default_value,否则返回value

nvl(T value, T default_value)

1 返回值：T

返回第一非null的值，如果全部都为NULL就返回NULL  如：COALESCE (NULL,44,55)=44/strong>

COALESCE(T v1, T v2, ...)

1 返回值：T

如果a=b就返回c,a=d就返回e，否则返回f  如CASE 4 WHEN 5  THEN 5 WHEN 4 THEN 4 ELSE 3 END 将返回4

CASE a WHEN b THEN c [WHEN d THEN e]* [ELSE f] END

1 返回值：T

如果a=ture就返回b,c= ture就返回d，否则返回e  如：CASE WHEN  5>0  THEN 5 WHEN 4>0 THEN 4 ELSE 0 END 将返回5；CASE WHEN  5<0  THEN 5 WHEN 4<0 THEN 4 ELSE 0 END 将返回0

CASE WHEN a THEN b [WHEN c THEN d]* [ELSE e] END

1 返回值：T

如果a为null就返回true，否则返回false

isnull( a )

1 返回值：boolean

如果a为非null就返回true，否则返回false

isnotnull ( a )

1 返回值：boolean

6.字符函数

 返回str中首个ASCII字符串的整数值

ascii(string str)

1 返回值：int

将二进制bin转换成64位的字符串

base64(binary bin)

1 返回值：string

对二进制字节码或字符串按次序进行拼接

concat(string|binary A, string|binary B...)

1 返回值：string

与ngram类似，但context_ngram()允许你预算指定上下文(数组)来去查找子序列，具体看(这里的解释更易懂)

context_ngrams(array<array<string>>, array<string>, int K, int pf)

1 返回值：array
    
     
      >
     
    

与concat()类似，但使用指定的分隔符喜进行分隔

concat_ws(string SEP, string A, string B...)

1 返回值：string

拼接Array中的元素并用指定分隔符进行分隔

concat_ws(string SEP, array<string>)

1 返回值：string

使用指定的字符集charset将字符串编码成二进制值，支持的字符集有：'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'，如果任一输入参数为NULL都将返回NULL

encode(string src, string charset)

1 返回值：binary

返回以逗号分隔的字符串中str出现的位置，如果参数str为逗号或查找失败将返回0，如果任一参数为NULL将返回NULL回

find_in_set(string str, string strList)

1 返回值：int

将数值X转换成"#,###,###.##"格式字符串，并保留d位小数，如果d为0，将进行四舍五入且不保留小数

format_number(number x, int d)

1 返回值：string

从指定路径上的JSON字符串抽取出JSON对象，并返回这个对象的JSON格式，如果输入的JSON是非法的将返回NULL,注意此路径上JSON字符串只能由数字 字母 下划线组成且不能有大写字母和特殊字符，且key不能由数字开头，这是由于Hive对列名的限制

get_json_object(string json_string, string path)

1 返回值：string

如果文件名为filename的文件中有一行数据与字符串str匹配成功就返回true

in_file(string str, string filename)

1 返回值：boolean

查找字符串str中子字符串substr出现的位置，如果查找失败将返回0，如果任一参数为Null将返回null，注意位置为从1开始的

instr(string str, string substr)

1 返回值：int

返回字符串的长度

length(string A)

1 返回值：int

查找字符串str中的pos位置后字符串substr第一次出现的位置

locate(string substr, string str[, int pos])

1 返回值：int

将字符串A的所有字母转换成小写字母

lower(string A) lcase(string A)

1 返回值：string

 

从左边开始对字符串str使用字符串pad填充，最终len长度为止，如果字符串str本身长度比len大的话，将去掉多余的部分

lpad(string str, int len, string pad)

1 返回值：string

去掉字符串A前面的空格

ltrim(string A)

1 返回值：string

返回出现次数TOP K的的子序列,n表示子序列的长度，具体看 (这里的解释更易懂)

ngrams(array<array<string>>, int N, int K, int pf)

1 返回值：array
    
     
      >
     
    

返回从URL中抽取指定部分的内容，参数url是URL字符串，而参数partToExtract是要抽取的部分，这个参数包含(HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, and USERINFO,例如：parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'HOST') ='facebook.com'，如果参数partToExtract值为QUERY则必须指定第三个参数key  如：parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'QUERY', 'k1') =‘v1’

parse_url(string urlString, string partToExtract [, string keyToExtract])

1 返回值：string

 

按照printf风格格式输出字符串

printf(String format, Obj... args)

1 返回值：string

抽取字符串subject中符合正则表达式pattern的第index个部分的子字符串，注意些预定义字符的使用，如第二个参数如果使用'\s'将被匹配到s,'\\s'才是匹配空格

regexp_extract(string subject, string pattern, int index)

1 返回值：string

 

按照Java正则表达式PATTERN将字符串INTIAL_STRING中符合条件的部分成REPLACEMENT所指定的字符串，如里REPLACEMENT这空的话，抽符合正则的部分将被去掉  如：regexp_replace("foobar", "oo|ar", "") = 'fb.' 注意些预定义字符的使用，如第二个参数如果使用'\s'将被匹配到s,'\\s'才是匹配空格

regexp_replace(string INITIAL_STRING, string PATTERN, string REPLACEMENT)

1 返回值：string

 

重复输出n次字符串str

repeat(string str, int n)

1 返回值：2 string

 

反转字符串

reverse(string A)

1 返回值：string

从右边开始对字符串str使用字符串pad填充，最终len长度为止，如果字符串str本身长度比len大的话，将去掉多余的部分

rpad(string str, int len, string pad)

1 返回值：string

 

去掉字符串后面出现的空格

rtrim(string A)

1 返回值：string

字符串str将被转换成单词数组，如：sentences('Hello there! How are you?') =( ("Hello", "there"), ("How", "are", "you") )

sentences(string str, string lang, string locale)

1 返回值：array
    
     
      >
     
    

返回n个空格

space(int n)

返回值：string

按照正则表达式pat来分割字符串str,并将分割后的数组字符串的形式返回

split(string str, string pat)

1 返回值：string

将字符串str按照指定分隔符转换成Map，第一个参数是需要转换字符串，第二个参数是键值对之间的分隔符，默认为逗号;第三个参数是键值之间的分隔符，默认为"="

str_to_map(text[, delimiter1, delimiter2])

1 返回值：map
    

 

对于字符串A,从start位置开始截取字符串并返回

substr(string|binary A, int start) substring(string|binary A, int start)

1 返回值：string

 

对于二进制/字符串A,从start位置开始截取长度为length的字符串并返回

substr(string|binary A, int start, int len) substring(string|binary A, int start, int len)

1 返回值：string

截取第count分隔符之前的字符串，如count为正则从左边开始截取，如果为负则从右边开始截取

substring_index(string A, string delim, int count)

1 返回值：string

将input出现在from中的字符串替换成to中的字符串 如：translate("MOBIN","BIN","M")="MOM"

translate(string|char|varchar input, string|char|varchar from, string|char|varchar to)

1 返回值：string

将64位的字符串转换二进制值

unbase64(string str)

1 返回值：binary

将字符串A中的字母转换成大写字母

upper(string A) ucase(string A)

1 返回值：string

将字符串A转换第一个字母大写其余字母的字符串

initcap(string A)

1 返回值：string

计算两个字符串之间的差异大小  如：levenshtein('kitten', 'sitting') = 3

levenshtein(string A, string B)

1 返回值：int

将普通字符串转换成soundex字符串

soundex(string A)

1 返回值：string

 

7.字符串函数

分割字符串函数: split

语法:  split(string str, string pat)

1 返回值:  array  2 说明: 按照pat字符串分割str，会返回分割后的字符串数组  3 举例：4 hive> select split('abtcdtef','t');5 OK6 ["ab","cd","ef"]7 Time taken: 0.118 seconds, Fetched: 1 row(s)

与GP，ORACLE不同，pad 不能默认

右补足函数：rpad

语法: rpad(string str, int len, string pad)

1 返回值: string  2 说明：将str进行用pad进行右补足到len位  3 举例：4 hive> 5     > select rpad('abc',10,'td');6 OK7 abctdtdtdt8 Time taken: 0.077 seconds, Fetched: 1 row(s)

左补足函数：lpad

语法: lpad(string str, int len, string pad)

1 hive> 2     > select rpad('abc',10,'td');3 OK4 abctdtdtdt5 Time taken: 0.077 seconds, Fetched: 1 row(s)

首字符ascii函数：ascii

语法: ascii(string str)

1 返回值: int  2 说明：返回字符串str第一个字符的ascii码  3 举例：  hive>  select ascii('abcde');4 OK5 976 Time taken: 0.066 seconds, Fetched: 1 row(s)

重复字符串函数：repeat

语法: repeat(string str, int n)

1 返回值: string  2 说明：返回重复n次后的str字符串  3 举例： 4  hive> select repeat('abc',5);5 OK6 abcabcabcabcabc7 Time taken: 0.064 seconds, Fetched: 1 row(s)

空格字符串函数：space

语法: space(int n)

1 返回值: string   2 说明：返回长度为n的字符串   3 举例：hive> select space(10); 4 OK 5            6 Time taken: 0.101 seconds, Fetched: 1 row(s) 7 hive> select length(space(10)); 8 OK 9 1010 Time taken: 1.905 seconds, Fetched: 1 row(s)

字符串长度函数：length

1 语法: length(string A)  2 返回值: int  3 说明：返回字符串A的长度  4 举例：hive> select length('abcedfg');5 OK6 77 Time taken: 0.065 seconds, Fetched: 1 row(s)

字符串反转函数：reverse

语法: reverse(string A)  返回值: string  说明：返回字符串A的反转结果  举例：  hive> select reverse('abcedfg');OKgfdecbaTime taken: 0.077 seconds, Fetched: 1 row(s)

字符串连接函数：concat

1 语法: concat(string A, string B…)  2 返回值: string  3 说明：返回输入字符串连接后的结果，支持任意个输入字符串  4 举例：hive>  select concat('abc','def','gh');5 OK6 abcdefgh7 Time taken: 0.063 seconds, Fetched: 1 row(s)

带分隔符字符串连接函数：concat_ws

语法: concat_ws(string SEP, string A, string B…)  返回值: string  说明：返回输入字符串连接后的结果，SEP表示各个字符串间的分隔符  举例：  hive> select concat_ws('-','abc','def','gh');OKabc-def-ghTime taken: 0.06 seconds, Fetched: 1 row(s)

字符串截取函数：substr,substring

1 语法: substr(string A, int start),substring(string A, int start)   2 返回值: string   3 说明：返回字符串A从start位置到结尾的字符串   4 举例： hive> select substr('abcde',3); 5 OK 6 cde 7 Time taken: 0.062 seconds, Fetched: 1 row(s) 8 hive> select substring('abcde',3); 9 OK10 cde11 Time taken: 0.05 seconds, Fetched: 1 row(s)12 hive> select substr('abcde',-1);13 OK14 e15 Time taken: 0.061 seconds, Fetched: 1 row(s)

字符串截取函数：substr,substring

1 语法: substr(string A, int start, int len),substring(string A, int start, int len)   2 返回值: string   3 说明：返回字符串A从start位置开始，长度为len的字符串   4 举例： 5 hive>  select substr('abcde',3,2); 6 OK 7 cd 8 Time taken: 0.07 seconds, Fetched: 1 row(s) 9 hive> select substring('abcde',3,2);10 OK11 cd12 Time taken: 0.062 seconds, Fetched: 1 row(s)13 hive> select substring('abcde',-2,2);14 OK15 de16 Time taken: 0.113 seconds, Fetched: 1 row(s)

字符串转大写函数：upper,ucase

1 语法: upper(string A) ucase(string A)   2 返回值: string   3 说明：返回字符串A的大写格式   4 举例：hive> select upper('abSEd'); 5 OK 6 ABSED 7 Time taken: 0.059 seconds, Fetched: 1 row(s) 8 hive> select ucase('abSEd'); 9 OK10 ABSED11 Time taken: 0.058 seconds, Fetched: 1 row(s)

字符串转小写函数：lower,lcase

1 语法: lower(string A) lcase(string A)   2 返回值: string   3 说明：返回字符串A的小写格式   4 举例：  5 hive> select lower('abSEd'); 6 OK 7 absed 8 Time taken: 0.068 seconds, Fetched: 1 row(s) 9 hive> select lcase('abSEd');10 OK11 absed12 Time taken: 0.057 seconds, Fetched: 1 row(s)

去空格函数：trim

1 语法: trim(string A)  2 返回值: string  3 说明：去除字符串两边的空格  4 举例：hive> select trim(' abc ');5 OK6 abc7 Time taken: 0.058 seconds, Fetched: 1 row(s)

左边去空格函数：ltrim

1 语法: ltrim(string A)  2 返回值: string  3 说明：去除字符串左边的空格  4 举例：  hive> select ltrim(' abc ');5 OK6 abc 7 Time taken: 0.059 seconds, Fetched: 1 row(s)

右边去空格函数：rtrim

1 语法: rtrim(string A)  2 返回值: string  3 说明：去除字符串右边的空格  4 举例：hive> select rtrim(' abc ');5 OK6  abc7 Time taken: 0.058 seconds, Fetched: 1 row(s)

正则表达式解析函数：regexp_extract

其中的index，是按照正则字符串（）的位置

1 语法: regexp_extract(string subject, string pattern, int index)   2 返回值: string   3 说明：将字符串subject按照pattern正则表达式的规则拆分，返回index指定的字符。注意，在有些情况下要使用转义字符   4 举例：  5  hive> select regexp_extract('foothebar', 'foo(.*?)(bar)', 1); 6 OK 7 the 8 Time taken: 0.389 seconds, Fetched: 1 row(s) 9 hive> select regexp_extract('foothebar', 'foo(.*?)(bar)', 2);10 OK11 bar12 Time taken: 0.051 seconds, Fetched: 1 row(s)13 hive>  select regexp_extract('foothebar', 'foo(.*?)(bar)', 0);14 OK15 foothebar16 Time taken: 0.058 seconds, Fetched: 1 row(s)

函数parse_url,解析URL字符串

1 parse_url(url, partToExtract[, key]) - extracts a part from a URL   2 解析URL字符串，partToExtract的选项包含[HOST,PATH,QUERY,REF,PROTOCOL,FILE,AUTHORITY,USERINFO]。  3 举例： 4 hive> select parse_url('http://facebook.com/path/p1.php?query=1', 'HOST') ; 5 OK 6 facebook.com 7 Time taken: 0.286 seconds, Fetched: 1 row(s) 8 hive> select parse_url('http://facebook.com/path/p1.php?query=1', 'PATH'); 9 OK10 /path/p1.php11 Time taken: 0.069 seconds, Fetched: 1 row(s)12 hive> select parse_url('http://facebook.com/path/p1.php?query=1', 'QUERY');13 OK14 query=115 可以指定key来返回特定参数，例如 16 Time taken: 0.21 seconds, Fetched: 1 row(s)17 hive> select parse_url('http://facebook.com/path/p1.php?query=1', 'QUERY','query');18 OK19 120 Time taken: 0.057 seconds, Fetched: 1 row(s)21 hive> select parse_url('http://facebook.com/path/p1.php?query=1#Ref', 'REF');22 OK23 Ref24 Time taken: 0.055 seconds, Fetched: 1 row(s)25 hive> select parse_url('http://facebook.com/path/p1.php?query=1#Ref', 'PROTOCOL');26 OK27 http28 Time taken: 0.06 seconds, Fetched: 1 row(s)

1 hive> select parse_url_tuple('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'QUERY:k1', 'QUERY:k2'); 2 OK3 v1      v24 Time taken: 0.2 seconds, Fetched: 1 row(s)

 

json解析函数：get_json_object

语法: get_json_object(string json_string, string path)

1 返回值: string   2 说明：解析json的字符串json_string,返回path指定的内容。如果输入的json字符串无效，那么返回NULL。   3 举例： hive> select get_json_object('{"store":{"fruit":\[{"weight":8,"type":"apple"},{"weight":9,"type":"pear"}],"bicycle":{"price":19.95,"color":"red"} }, "email":"amy@only_for_json_udf_test.net","owner":"amy"}','$.store');  4 OK 5 {"fruit":[{"weight":8,"type":"apple"},{"weight":9,"type":"pear"}],"bicycle":{"price":19.95,"color":"red"}} 6 Time taken: 0.108 seconds, Fetched: 1 row(s) 7  8 hive> select get_json_object('{"store":{"fruit":\[{"weight":8,"type":"apple"},{"weight":9,"type":"pear"}],"bicycle":{"price":19.95,"color":"red"} }, "email":"amy@only_for_json_udf_test.net","owner":"amy"}','$.email');  9 OK10 amy@only_for_json_udf_test.net11 12 hive> select get_json_object('{"store":{"fruit":\[{"weight":8,"type":"apple"},{"weight":9,"type":"pear"}],"bicycle":{"price":19.95,"color":"red"} }, "email":"amy@only_for_json_udf_test.net","owner":"amy"}','$.owner'); 13 OK14 amy15 Time taken: 0.499 seconds, Fetched: 1 row(s)

 行转列：explode （posexplode Available as of Hive 0.13.0）

1 说明：将输入的一行数组或者map转换成列输出 2 语法：explode(array (or map)) 3 举例： 4  5 hive> select explode(split(concat_ws('-','1','2','3','4','5','6','7','8','9'),'-'));   6 OK 7 1 8 2 9 310 411 512 613 714 815 916 Time taken: 0.095 seconds, Fetched: 9 row(s)

 

二.集合函数

集合查找函数: find_in_set

语法: find_in_set(string str, string strList)

返回值: int  说明: 返回str在strlist第一次出现的位置，strlist是用逗号分割的字符串。如果没有找该str字符，则返回0  举例： hive> select find_in_set('ab','ef,ab,de');OK2Time taken: 2.336 seconds, Fetched: 1 row(s)hive> select find_in_set('at','ef,ab,de');OK0Time taken: 0.094 seconds, Fetched: 1 row(s)

 

hive提供了复合数据类型：

Structs： structs内部的数据可以通过DOT（.）来存取，例如，表中一列c的类型为STRUCT{a INT; b INT}，我们可以通过c.a来访问域a

Maps（K-V对）：访问指定域可以通过["指定域名称"]进行，例如，一个Map M包含了一个group-》gid的kv对，gid的值可以通过M[' group']来获取

Arrays：array中的数据为相同类型，例如，假如array A中元素['a','b','c']，则A[1]的值为'b'

Struct使用

1 create table qa_test.student_test(id INT, info struct
    
     )   2 ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' 3 COLLECTION ITEMS TERMINATED BY ':'; 4  5 hive> desc qa_test.student_test; 6 OK 7 id                      int 8 info                    struct
     
       9 Time taken: 0.048 seconds, Fetched: 2 row(s)10 11 12 $cat test5.txt13 1,zhou:3014 2,yan:3015 3,chen:2016 4,li:8017 18 19 LOAD DATA LOCAL INPATH '/home/hadoop/test/test5' INTO TABLE qa_test.student_test;20 21 hive> select  *  from qa_test.student_test;22 OK23 1       {"name":"zhou","age":30}24 2       {"name":"yan","age":30}25 3       {"name":"chen","age":20}26 4       {"name":"li","age":80}27 28 29 hive> select info.age from qa_test.student_test;30 OK31 3032 3033 2034 8035 Time taken: 0.234 seconds, Fetched: 4 row(s)36 hive> select info.name from qa_test.student_test;37 OK38 zhou39 yan40 chen41 li42 Time taken: 0.08 seconds, Fetched: 4 row(s)
     
    

Array使用

1 create table qa_test.class_test(name string, student_id_list array
    
     ) 2 ROW FORMAT DELIMITED 3 FIELDS TERMINATED BY ',' 4 COLLECTION ITEMS TERMINATED BY ':'; 5  6 hive>desc qa_test.class_test; 7 OK 8 name                    string 9 student_id_list         array
     
      10 Time taken: 0.052 seconds, Fetched: 2 row(s)11 12 $ cat test6.txt   13 034,1:2:3:414 035,5:615 036,7:8:9:1016 17 LOAD DATA LOCAL INPATH '/home/hadoop/test/test6' INTO TABLE qa_test.class_test;18 19 hive> select * from qa_test.class_test;20 OK21 034     [1,2,3,4]22 035     [5,6]23 036     [7,8,9,10]24 Time taken: 0.076 seconds, Fetched: 3 row(s)25 26 select student_id_list[3] from qa_test.class_test;27 28 hive> select student_id_list[3] from qa_test.class_test;29 OK30 431 NULL32 1033 Time taken: 0.12 seconds, Fetched: 3 row(s)34 35 hive> select size(student_id_list) from qa_test.class_test;36 OK37 438 239 440 Time taken: 0.086 seconds, Fetched: 3 row(s)41 42 43 hive> select array_contains(student_id_list,4) from qa_test.class_test;44 OK45 true46 false47 false48 Time taken: 0.129 seconds, Fetched: 3 row(s)49 50 hive> 51     > select   sort_array(student_id_list) from qa_test.class_test;52 OK53 [1,2,3,4]54 [5,6]55 [7,8,9,10]56 Time taken: 0.085 seconds, Fetched: 3 row(s)
     
    

Map使用

1 create table qa_test.employee(id string, perf map
    
     ) 2 ROW FORMAT DELIMITED 3 FIELDS TERMINATED BY '\t' 4 COLLECTION ITEMS TERMINATED BY ',' 5 MAP KEYS TERMINATED BY ':'; 6  7  8 $ cat test7.txt 9 1    job:80,team:60,person:7010 2    job:60,team:8011 3    job:90,team:70,person:10012 13 LOAD DATA LOCAL INPATH '/home/hadoop/test/test7' INTO TABLE qa_test.employee;14 15 hive> select * from qa_test.employee;16 OK17 1       {"job":80,"team":60,"person":70}18 2       {"job":60,"team":80}19 3       {"job":90,"team":70,"person":100}20 Time taken: 0.075 seconds, Fetched: 3 row(s)21 22 hive> select perf['job'] from qa_test.employee where perf['job'] is not null;   23 OK24 8025 6026 9027 Time taken: 0.096 seconds, Fetched: 3 row(s)28 29 hive> select size(perf) from qa_test.employee;   30 OK31 332 233 334 Time taken: 0.091 seconds, Fetched: 3 row(s)35 36 hive> select map_keys(perf) from qa_test.employee;   37 OK38 ["job","team","person"]39 ["job","team"]40 ["job","team","person"]41 Time taken: 0.136 seconds, Fetched: 3 row(s)42 43 hive> select map_values(perf) from qa_test.employee;   44 OK45 [80,60,70]46 [60,80]47 [90,70,100]48 Time taken: 0.077 seconds, Fetched: 3 row(s)
    

求map的长度 size(Map<K.V>)

1 返回值：int2 hive> select size(perf) from qa_test.employee;   3 OK4 35 26 37 Time taken: 0.091 seconds, Fetched: 3 row(s)

求数组的长度 size(Array<T>)

1 返回值：int2 hive> select size(student_id_list) from qa_test.class_test;3 OK4 45 26 47 Time taken: 0.086 seconds, Fetched: 3 row(s)

返回map中的所有key

map_keys(Map<K.V>)

1 返回值：array
    
     2 hive> select map_keys(perf) from qa_test.employee;   3 OK4 ["job","team","person"]5 ["job","team"]6 ["job","team","person"]7 Time taken: 0.136 seconds, Fetched: 3 row(s)
    

返回map中的所有value map_values(Map<K.V>)

1 返回值：array
    
     2 hive> select map_values(perf) from qa_test.employee;   3 OK4 [80,60,70]5 [60,80]6 [90,70,100]7 Time taken: 0.077 seconds, Fetched: 3 row(s)
    

如该数组Array<T>包含value返回true。，否则返回false array_contains(Array<T>, value)

1 返回值：boolean2 hive> select array_contains(student_id_list,4) from qa_test.class_test;3 OK4 true5 false6 false7 Time taken: 0.129 seconds, Fetched: 3 row(s)

按自然顺序对数组进行排序并返回 sort_array(Array<T>)

1 返回值：array2 hive> select   sort_array(student_id_list) from qa_test.class_test;3 OK4 [1,2,3,4]5 [5,6]6 [7,8,9,10]7 Time taken: 0.085 seconds, Fetched: 3 row(s)

 

二.聚合函数

 统计总行数，包括含有NULL值的行  count(*)

统计提供非NULL的expr表达式值的行数 count(expr)

统计提供非NULL且去重后的expr表达式值的行数  count(DISTINCT expr[, expr])

1 返回值：BIGINT

sum(col),表示求指定列的和，sum(DISTINCT col)表示求去重后的列的和

1 返回值：DOUBLE

avg(col),表示求指定列的平均值，avg(DISTINCT col)表示求去重后的列的平均值

1 返回值：DOUBLE

求指定列的最小值 min(col)

1 返回值：DOUBLE

求指定列的最大值 max(col)

1 返回值：DOUBLE

求指定列数值的方差 variance(col), var_pop(col)

1 返回值：DOUBLE

求指定列数值的样本方差

var_samp(col)

1 返回值：DOUBLE

求指定列数值的标准偏差

stddev_pop(col)

1 返回值：DOUBLE

求指定列数值的样本标准偏差

stddev_samp(col)

1 返回值：DOUBLE

求指定列数值的协方差 covar_pop(col1, col2)

1 返回值：DOUBLE

求指定列数值的样本协方差 covar_samp(col1, col2)

1 返回值：DOUBLE

返回两列数值的相关系数 corr(col1, col2)

1 返回值：DOUBLE

返回col的p%分位数  percentile(BIGINT col, p)

1 返回值：DOUBLE

 

三.特殊函数

窗口函数

 

分析函数

 

混合函数

 

UDTF

多行转换：lateral view

说明：lateral view用于和json_tuple，parse_url_tuple，split, explode等UDTF一起使用，它能够将一行数据拆成多行数据，在此基础上可以对拆分后的数据进行聚合。

举例：

1 说明：lateral view用于和json_tuple，parse_url_tuple，split, explode等UDTF一起使用，它能够将一行数据拆成多行数据，在此基础上可以对拆分后的数据进行聚合。 2 举例： 3  4     hive> select s.x,sp from test.dual s lateral view explode(split(concat_ws(',','1','2','3','4','5','6','7','8','9'),',')) t as sp;   5     x sp   6     a 1   7     b 2   8     a 3   9 解释一下，from后面是你的表名，在表名后面加lateral view explode。。。（你的行转列sql） ，还必须要起一个别名，我这个字段的别名为sp。然后再看看select后面的 s.*，就是原表的字段，我这里面只有一个字段，且为X10 11 多个lateral view的sql类如：12 13     SELECT * FROM exampleTable LATERAL VIEW explode(col1) myTable1 AS myCol1 LATERAL VIEW explode(myCol1) myTable2 AS myCol2;

抽取一行数据转换到新表的多列样例：

http_referer是获取的带参数请求路径，其中非法字符用\做了转义，根据路径解析出地址，查询条件等存入新表中，

1 drop table if exists t_ods_tmp_referurl;   2 create table t_ ods _tmp_referurl as   3 SELECT a.*,b.*   4 FROM ods_origin_weblog a LATERAL VIEW parse_url_tuple(regexp_replace(http_referer, "\"", ""), 'HOST', 'PATH','QUERY', 'QUERY:id') b as host, path, query, query_id;  5  6 复制表，并将时间截取到日： 7 drop table if exists t_ods_tmp_detail;   8 create table t_ods_tmp_detail as    9 select b.*,substring(time_local,0,10) as daystr,  10 substring(time_local,11) as tmstr,  11 substring(time_local,5,2) as month,  12 substring(time_local,8,2) as day,  13 substring(time_local,11,2) as hour  14 From t_ ods _tmp_referurl b;

 表生成函数

对于a中的每个元素，将生成一行且包含该元素

explode(array<TYPE> a)

1 返回值：Array Type

每行对应数组中的一个元素 explode(ARRAY)

1 返回值：N rows

每行对应每个map键-值，其中一个字段是map的键，另一个字段是map的值

explode(MAP)

1 返回值：N rows

explode类似，不同的是还返回各元素在数组中的位置

posexplode(ARRAY)

1 返回值：N rows

把M列转换成N行，每行有M/N个字段，其中n必须是个常数

stack(INT n, v_1, v_2, ..., v_k)

1 返回值：N rows

从一个JSON字符串中获取多个键并作为一个元组返回，与get_json_object不同的是此函数能一次获取多个键值

json_tuple(jsonStr, k1, k2, ...)

1 返回值：tuple

返回从URL中抽取指定N部分的内容，参数url是URL字符串，而参数p1,p2,....是要抽取的部分，这个参数包含HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, USERINFO, QUERY:<KEY>

1 返回值；tuple

将结构体数组提取出来并插入到表中 inline(ARRAY<STRUCT[,STRUCT]>)

 

下表为Hive内置的聚合函数。

返回类型	函数名	描述
BIGINT	count(*) count(expr) count(DISTINCT expr[, expr_.])	count(*) – 返回检索到的行的总数，包括含有NULL值的行。count(expr) – 返回expr表达式不是NULL的行的数量count(DISTINCT expr[, expr]) – 返回expr是唯一的且非NULL的行的数量
DOUBLE	sum(col) sum(DISTINCT col)	对组内某列求和（包含重复值）或者对组内某列求和（不包含重复值）
DOUBLE	avg(col), avg(DISTINCT col)	对组内某列元素求平均值者（包含重复值或不包含重复值）
DOUBLE	min(col)	返回组内某列的最小值
DOUBLE	max(col)	返回组内某列的最大值
DOUBLE	variance(col), var_pop(col)	返回组内某个数字列的方差
DOUBLE	var_samp(col)	返回组内某个数字列的无偏样本方差
DOUBLE	stddev_pop(col)	返回组内某个数字列的标准差
DOUBLE	stddev_samp(col)	返回组内某个数字列的无偏样本标准差
DOUBLE	covar_pop(col1, col2)	返回组内两个数字列的总体协方差
DOUBLE	covar_samp(col1, col2)	返回组内两个数字列的样本协方差
DOUBLE	corr(col1, col2)	返回组内两个数字列的皮尔逊相关系数
DOUBLE	percentile(BIGINT col, p)	返回组内某个列精确的第p位百分数，p必须在0和1之间
array<double>	percentile(BIGINT col, array(p1 [, p2]...))	返回组内某个列精确的第p1，p2，……位百分数，p必须在0和1之间
DOUBLE	percentile_approx(DOUBLE col, p [, B])	返回组内数字列近似的第p位百分数（包括浮点数），参数B控制近似的精确度，B值越大，近似度越高，默认值为10000。当列中非重复值的数量小于B时，返回精确的百分数
array<double>	percentile_approx(DOUBLE col, array(p1 [, p2]...) [, B])	同上，但接受并返回百分数数组
array<struct {'x','y'}>	histogram_numeric(col, b)	使用b个非均匀间隔的箱子计算组内数字列的柱状图（直方图），输出的数组大小为b，double类型的(x,y)表示直方图的中心和高度
array	collect_set(col)	返回消除了重复元素的数组
array	collect_list(col)	返回允许重复元素的数组
INTEGER	ntile(INTEGER x)	该函数将已经排序的分区分到x个桶中，并为每行分配一个桶号。这可以容易的计算三分位，四分位，十分位，百分位和其它通用的概要统计

内置 Table-Generating函数（UDTF）

正常的用户定义函数，如concat，输入一个单行然后输出一个单行，但table-generating函数将一个单输入行转换为多个输出行。下表为Hive内置的table-generating函数。

返回类型	函数名	描述
N rows	explode(ARRAY)	参数列为数组类型，将数组数据中的每个元素做为一行返回
N rows	explode(MAP)	将输入map中的每个键值对转换为两列，一列为key，另一列为value，然后返回新行
	inline(ARRAY<STRUCT[,STRUCT]>)	分解struct数组到表中
Array Type	explode(array<TYPE> a)	对于数组a中的每个元素，该函数产生包含该元素的行For
元组	json_tuple(jsonStr, k1, k2, ...)	参数为一组键k1，k2……和JSON字符串，返回值的元组。该方法比 get_json_object 高效，因为可以在一次调用中输入多个键
元组	parse_url_tuple(url, p1, p2, ...)	该方法同parse_url() 相似，但可以一次性提取URL的多个部分，有效的参数名称为： HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, USERINFO, QUERY:<KEY>
N rows	posexplode(ARRAY)	行为与参数为数组的explode方法相似，但包含项在原始数组中的位置，返回(pos,value)的二元组
	stack(INT n, v_1, v_2, ..., v_k)	将v_1, ..., v_k 分为n行，每行包含n/k列，n必须为常数

使用语法”SELECT udtf(col) AS colAlias...”有以下几点限制：

 

•  在SELECT中不允许再有其他表达式：不支持SELECT pageid, explode(adid_list) AS myCol...
•  UDTF不能够嵌套使用：不支持SELECT explode(explode(adid_list)) AS myCol...
• 不支持GROUP BY /CLUSTER BY / DISTRIBUTE BY / SORT BY：不支持SELECT explode(adid_list) AS myCol ... GROUP BY myCol